The present invention relates to nonwoven fibrous non-elastic material, and reinforced nonwoven fibrous material, wherein the nonwoven fibrous material is a hydraulically entangled coform (e.g., admixture) of non-elastic meltblown fibers and fibrous material (e.g., non-elastic fibrous material), with or without particulate material. The fibrous material can be at least one of pulp fibers, staple fibers, meltblown fibers and continuous filaments. Such material has applications for wipes, tissues and garments, among other uses.
Moreover, the present invention relates to methods of forming such nonwoven material and methods of forming reinforced nonwoven material by hydraulic entangling techniques.
It has been desired to provide a coform having increased web strength, low linting and high durability without a significant loss of the web's drape, bulk and cloth-like hand. Moreover, it has been desired to provide such coform materials as part of, e.g., a laminate, having various uses such as in protective clothing, wipes and as cover-stock for personal care absorbent products.
U.S. Pat. No. 4,100,324 to Anderson et al, the contents of which are incorporated herein by reference, discloses a nonwoven fabric-like composite material which consists essentially of an air-formed matrix of thermoplastic polymer microfibers having an average fiber diameter of less than about 10 microns, and a multiplicity of individualized wood pulp fibers disposed throughout the matrix of microfibers and engaging at least some of the microfibers to space the microfibers apart from each other. This patent discloses that the wood pulp fibers can be interconnected by and held captive within the matrix of microfibers by mechanical entanglement of the microfibers with the wood pulp fibers, the mechanical entanglement and interconnection of the microfibers and wood pulp fibers alone, without additional bonding, e.g., thermal, resin, etc., and thus forming a coherent integrated fibrous structure. However, the strength of the web can be improved by embossing the web either ultrasonically or at an elevated temperature so that the thermoplastic microfibers are flattened into a film-like structure in the embossed areas. Additional fibrous and/or particulate materials including synthetic fibers such as staple nylon fibers and natural fibers such as cotton, flax, jute and silk can be incorporated in the composite material. The material is formed by initially forming a primary air stream containing meltblown microfibers, forming a secondary air stream containing wood pulp fibers (or wood pulp fibers and/or other fibers, with or without particulate material), merging the primary and secondary streams under turbulent conditions to form an integrated air stream containing a thorough mixture of the microfibers and wood pulp fibers, and then directing the integrated air stream onto a forming surface to air-form the fabric-like material.
U.S. Pat. No. 4,118,531 to Hauser relates to microfiber-based webs containing mixtures of microfibers and crimped bulking fibers. This patent discloses that crimped bulking fibers are introduced into a stream of blown microfibers. The mixed stream of microfibers and bulking fibers then continues to a collector where a web of randomly intermixed and intertangled fibers is formed.
U.S. Pat. No. 3,485,706 to Evans discloses a textile-like nonwoven fabric and a process and apparatus for its production, wherein the fabric has fibers randomly entangled with each other in a repeating pattern of localized entangled regions interconnected by fibers extending between adjacent entangled regions. The process disclosed in this patent involves supporting a layer of fibrous material on an apertured patterning member for treatment, jetting liquid supplied at pressures of at least 200 pounds per square inch psi) gage to form streams having over 23,000 energy flux in foot-poundals/inch.sup.2 . second at the treatment distance, and traversing the supporting layer of fibrous material with the streams to entangle fibers in a pattern determined by the supporting member, using a sufficient amount of treatment to produce uniformly patterned fabric. The initial material is disclosed to consist of any web, mat, batt or the like of loose fibers disposed in random relationship with one another or in any degree of alignment.
U.S. Pat. No. Re. 31,601 to Ikeda et al discloses a fabric, useful as a substratum for artificial leather, which comprises a woven or knitted fabric constituent and a nonwoven fabric constituent. The nonwoven fabric constituent consists of numerous extremely fine individual fibers which have an average diameter of 0.1 to 6.0 microns and are randomly distributed and entangled with each other to form a body of nonwoven fabric. The nonwoven fabric constituent and the woven or knitted fabric constituent are superimposed and bonded together, to form a body of composite fabric, in such a manner that a portion of the extremely fine individual fibers and the nonwoven fabric constituent penetrate into the inside of the woven or knitted fabric constituent and are entangled with a portion of the fibers therein. The composite fabric is disclosed to be produced by superimposing the two fabric constituents on each other and jetting numerous fluid streams ejected under a pressure of from 15 to 100 kg/cm.sup.2 toward the surface of the fibrous web constituent. This patent discloses that the extremely fine fibers can be produced by using any of the conventional fiber-producing methods, preferably a meltblown method.
U.S. Pat. No. 4,190,695 to Niederhauser discloses lightweight composite fabrics suitable for general purpose wearing apparel, produced by a hydraulic needling process from short staple fibers and a substrate of continuous filaments formed into an ordered cross-directional array, the individual continuous filaments being interpenetrated by the short staple fibers and locked in place by the high frequency of staple fiber reversals. The formed composite fabrics can retain the staple fibers during laundering, and have comparable cover and fabric aesthetics to woven materials of higher basis weight.
U.S. Pat. No. 4,426,421 to Nakamae et al discloses a multi-layer composite sheet useful as a substrate for artificial leather, comprising at least three fibrous layers, namely, a superficial layer consisting of spun-laid extremely fine fibers entangled with each other, thereby forming a body of a nonwoven fibrous layer; an intermediate layer consisting of synthetic staple fibers entangled with each other to form a body of nonwoven fibrous layer; and a base layer consisting of a woven or knitted fabric. The composite sheet is disclosed to be prepared by superimposing the layers together in the aforementioned order and, then, incorporating them together to form a body of composite sheet by means of a needle-punching or water-stream-ejecting under a high pressure. This patent discloses that the spun-laid extremely fine fibers can be produced by the meltblown method.
U.S. Pat. No. 4,442,161 to Kirayoglu et al discloses a spunlaced (hydraulically entangled) nonwoven fabric and a process for producing the fabric, wherein an assembly consisting essentially of wood pulp and synthetic organic fibers is treated, while on a supporting member, with fine columnar jets of water. This patent discloses it is preferred that the synthetic organic fibers be in the form of continuous filament nonwoven sheets and the wood pulp fibers be in the form of paper sheets.
Existing hydraulically entangled materials suffer from a number of problems. Such materials do not exhibit isotropic properties, are not durable (e.g., do not have good pill resistance) and do not have enough abrasion resistance. Therefore, it is desired to provide a nonwoven web material having high web strength and integrity, lower linting and high durability without a significant loss of the web's drape, bulk and cloth-like hand. Moreover, it is desired to provide a process for producing such a material which allows for control of other product attributes, such as absorbency, isotropic properties, wet strength, barrier properties, printability and abrasion resistance.